Crane



' Filed Sept. 19, 1950 A. s. STOKES 2,722,319

CRANE Nov. 1 1955 5 Sheets-Sheet 1 Attorney Nov. 1, 1955 A. s. STOKES2,722,319

CRANE Filed Sept. 19, 1950 5 Sheets-Sheet 2 Inventor 4/v7-a/vy 56077570x55,

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CRANE Filed Sept. 19, 1 50 5 Sheets-Sheet 4 Inventor flA m/vy \scarr 6701(56 MQQ Attorney United States Patent CRANE Antony Scott Stokes,Ipswich, England, assignor to Rausomes & Rapier Limited, Ipswich,England Application September 19, 1950, Serial No. 185,565

4 Claims. (Cl. 212-8) Cranes used for unloading ships at a dockside haveoften tooperate under cramped conditions and satisfy exactingrequirements. Preferably they should be able to raise a load from thefurther side of a hold and lower it either as close as possible to thefoot of the crane or at'the greatest possible distance from it invarious directions. At the same time the jib must clear obstructionssuch as the rigging and near rail of a ship. Such cranes are sometimescarried on a'high gantry which runs on rails, but these are bulky, heavyand therefore more expensive to build than cranes with a jib mounted ona comparatively low and narrow base. The outwards derricking of a jib ona low base, however, is limited by obstructions such as the near rail ofthe ship and a good outreach can only be obtained with a jib that iseither inconveniently long or is bent. A long-reaching jib is relativelyheavy, slow in operation and difiicult to keep clear of rigging, as alsois a permanently bent jib, which becomes undesirably twisted when beingslewed, and neither can be derricked in as much as is desirable to allowa load to be dropped close to the base of the crane.

It is an object of the present invention to provide a crane with a jibwhich can be mounted on a low base and yet manoeuvred clear ofobstructions.

It is a further object to provide a crane having a jib in two partsmovable by a single winding motor.

Further objects and advantages of the present invention will appear fromthe following description of one embodiment, reference being made to theaccompanying drawings in which:

Figure 1 is a side elevation of the crane;

Figure 2 is an enlarged view of the lower part of Figure 1;

Figure 3 is a diagram illustrating the threading of the hoisting andderricking ropes;

Figures 4 to 8 are diagrams illustrating the operation of the crane; and

Fig. 9 is a rear elevational view of the lower portion of the crane.

Essentially the crane comprises a main jib pivoted to a base, anextension pivoted to the head of the main jib, and derricking mechanismcontrolling both the main jib and the extension and so arranged that inderricking out the extension turns through a greater angle towards thehorizontal than does the main jib.

The crane consists of a wheeled chassis 2 on which is mounted aturn-table 4 carrying A-frames 6, a cab 8 and a counterweight 10. Themain jib 12 of the crane is pivoted to the frames 6 about an axis 14 andat its upper end carries an extension 16 pivoted to the head of the mainjib at 18. A triangular frame 20 forming the heel of the extension isalso pivoted at 18 and is joined to the head of the extension by ties22.

Derricking of the crane is controlled by a rope 24 which is at one endanchored to a shaft 26 carried in brackets 28 on the main jib. This ropepasses round a pulley 30 on a shaft 32 carried by the frame 20, thenround a guide pulley 34 on the shaft 26 and thence in succession roundpulleys 36, 38, 40, 42 and 44 carried by a shaft 46 at the heel of themain jib and by a shaft 48 at the rear of the cab 8. Finally, the rope24-is wound on a barrel 50 on the shaft 48. When .the rope 24 is woundonto the barrel 50 it tends to raise both the main jib 12 and theextension 16. The weights of the ,main jib and the extension, and thenumbers of parts 'of the rope 24 acting on their heels are such thatthe-main jib is raised in preference to the extension.

tion which in the example is directly in line with the mains stationarywhile the extension 16 turns towards the horizontal and the cranereaches a position shown in Figure 5. Rotation of the extension relativeto the main jib is limited by ties 54 which are pivoted to the frame 20'at 56, and at their lower ends are linked by a cross-bar":

.58 sliding in slots on the main jib 12. After the crossbar 58 hasreached the upper end of the slots further unwinding of the rope 24allows the main jib and ex- ,tension to turn together towards thehorizontal until they 'ireach a position shown in Figure 6. It will beseen that the sequence of movements of the main jib and extension isunder the single control of the rope 24 and thus only a single barreland driving motor are necessary to raise and lower both the main jib andthe extension.

The ratio of the forces required on the heels of the extension and themain jib to support them varies according to the load which the crane iscarrying. To compensate for this, a hoisting rope 62, which is wound ona barrel 64, after passing over a guide pulley 66, is led round a pulley68 on the shaft 32, a pulley 70 on the shaft 26 and a further pulley 72on the shaft 32 before passing over a pulley 74 at the head of theextension 16. The tension in the rope 62 thus contributes to the forceon the heel of the extension 16 to an extent dependent on the loadsupported.

The value of the movement of the extension 16 relative to the main jib12 between the position shown in Figures 4 and 5 is illustrated inFigure l, where the outline 76 represents the near side of a ship havinga hatch opening 78. A straight jib which would both clear the rail ofthe ship and lower a load into the hold would have to be considerablylonger than the combined lengths of the extension and main jib of thecrane shown. The present crane is not however confined to this use, andprovision is made, if desired, for restricting or preventing relativemovement of the extension and the main jib 12 by means of a catch 80which can be swung about the axis 14 so as to obstruct partially orcompletely movement of the cross-bar 58 in the slot 60. The crane canthen move from the position shown in Figure 4 to that shown in Figure 8.This may be of value in clearing overhead obstructions.

The extension 16 is also fitted with a second set of ties 82 pivoted at56 and joined by a cross-bar 84. This bar 84 usually rests on the ties54, but if the main jib is lowered below the position shown in Figure 6,the bar 84 engages an upstanding abutment 86 fixed to the frame 6. Theeffect of this is to stop further rotation of the extension 16 relativeto the horizontal so that the lowermost position reached by the crane isthat shown in Figure 7 in which the extension has reverted to a positionin .line with the main jib. This enables the head of the extension toenter the doors of warehouses and the like.

I claim:

1. In a crane, in combination, a base, a main jib pivoted to said base,an extension pivoted to the head of said main Patented Nov. 1,,1955'Upward movement of the main jib 12 is limited by engagement of its heelwith a cross-bar 52. After the jib has engaged .this cross-bar furtherwinding of the rope 24 onto the barrel 50 raises the extension 16 to itsuppermost posijib, a tie having one end pivoted to said extension andthe other end mounted for limited movement relative to said main jib,and derricking mechanism connected to said main jib and extension topermit pivotal movement of said jib and extension in a derricking-outdirection whereby in derriclring out said extension rotates towards thehorizontal through an angle greater than that through which the main jibrotates by an amount determined by the extent of said sliding movement.

2. In a crane, in combination, a base, a main jib pivoted to said base,an extension pivoted to the head of said main jib, a tie having one endpivoted to said extension and the other end connected for limitingsliding movement relafive to said main jib, pulleys on said extension,said main jib and said base anda single derricking rope passing roundsaid pulleys and means controlling the movement of said rope todetermine the position of both said main jib. and said extension.

3. In a crane, in combination, a base, a main jib pivoted to said base,an extension pivoted to the head of said main jib, a tie having one endpivoted to said extension and the other end connected for limitedsliding movement relative to said main jib, means for selectivelyvarying the extent of said sliding movement, and derricking mechanismconnected to said main jib and extension to permit pivotal movement ofsaid jib and extension in a derricking-out direction whereby inderricking-out said extension rotates towards. the horizontal through anangle greater than that through which the main jib rotates by an amountdetermined by the extent of said sliding movement.

4. In a crane, in combination, a base, a main jib pivoted to said base,an extension pivoted to the head of said main jib, slidable meansinterconnecting said main jib and said extension for limiting relativemovement of said extension with respect to said main jib, pulleys onsaid extension, said main jib and said base and a single derricking ropepassing round said pulleys and means controlling the movement of saidrope to determine the position of both said main jib and said extension.

References Cited in the file of this patent UNITED STATES PATENTS970,773 Wylie Sept. 20, 1910 1,920,370 Forsythe et a1. Aug. 1. 19,3312,031,549 Rufi Feb. 18, 1936 2,524,748 Baker Oct. 10, 1950,

FOREIGN PATENTS 470,295 Great Britain Aug. 12, 1937 955,073 France June20, 1949

